Congrats on the new acquisition.

Keep in mind that the condition of your platen can have a pronounced effect on how loud a typewriter is; an SF with a rock-hard platen next to one with fresh rubber will sound louder - or at the very least more irritating. Years ago I tested a number of different silent/quiet/noiseless models against their regular counterparts and found the sound levels to be closer than expected. The tone of a machine makes a big difference though, and the lower frequency thudding of a Noiseless versus a higher pitch tapping of a regular portable is definitely easier to deal with.

The rubber on the platen really makes all the difference, so does the dampening Foam or Felt applied on the inside of many typewriters, especially portables. Putting your machines on a thick Felt ped dampens the noise even further. I once had the opportunity to try out an Overhauled Continental Silenta, and that was by far the most silent machine I have ever seen, that the platens of that one was not even re-done. Quite amazing mechanism on these Silentas.